fix(aws-lambda): Attach user info when streaming spans

[sentrivana]

Add user info onto streamed spans since they don't go through the event processor.

[github-actions]

Codecov Results 📊

✅ 130608 passed | ❌ 1 failed | ⏭️ 7126 skipped | Total: 137735 | Pass Rate: 94.83% | Execution Time: 477m 59s

📊 Comparison with Base Branch

Metric	Change
Total Tests	📉 -16
Passed Tests	📉 -17
Failed Tests	📈 +1
Skipped Tests	—

➕ New Tests (1)

View new tests

• test_cache_prefixes[False]
  • File: tests.integrations.redis.test_redis_cache_module
  • Status: ❌ Failing

❌ Failed Tests

test_cache_prefixes[False]

File: tests.integrations.redis.test_redis_cache_module
Suite: py3.7-redis-v4.6.0
Error: AssertionError: assert 'ܽr/٘F̞\x04?\x1a[\x1ezv, yes' == ', yes' + ܽr/٘F̞#x04?#x1A[#x1E - , yes + zv, yes ? ++

Stack Trace

tests/integrations/redis/test_redis_cache_module.py:446: in test_cache_prefixes
    assert cache_spans[4]["description"] == ", yes"
E   AssertionError: assert 'ܽr/٘F̞\x04?\x1a[\x1ezv, yes' == ', yes'
E     + ܽr/٘F̞#x04?#x1A[#x1E
E     - , yes
E     + zv, yes
E     ? ++

❌ Patch coverage is 3.13%. Project has 2521 uncovered lines.
❌ Project coverage is 90.21%. Comparing base (611584b) to head (abad60f).

Files with missing lines (1)

File	Patch %	Lines
sentry_sdk/integrations/aws_lambda.py	3.13%	⚠️ 31 Missing

Coverage diff

@@            Coverage Diff             @@
##        master       #PR       +/-##
==========================================
- Coverage    90.26%    90.21%    -0.05%
==========================================
  Files          193       193         —
  Lines        25729     25741       +12
  Branches      9496      9510       +14
==========================================
+ Hits         23221     23220        -1
- Misses        2508      2521       +13
- Partials      1434      1436        +2

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[cursor]

Cursor Bugbot has reviewed your changes and found 1 potential issue.

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[sentry-warden]

_get_user_from_event crashes when requestContext is None or non-dict

Guard requestContext and identity with isinstance(..., dict) before calling .get(); dict.get("requestContext", {}) still returns None when the key is present, and this helper now runs on the request path outside capture_internal_exceptions.

Evidence

• _get_user_from_event() does aws_event.get("requestContext", {}).get("identity"), which raises AttributeError if requestContext is explicitly None or otherwise non-dict.
• After the identity is None check, it calls identity.get(...) with no dict check, so a non-dict identity also raises.
• The new streaming path calls this helper via scope.set_user(...) outside the nearby capture_internal_exceptions() block, so the exception can fail the Lambda invocation.
• The same handler already special-cases non-dict headers for this reason, but user extraction does not.

_{Identified by Warden · code-review · QYJ-NUN}